The postcss-theme-provider package version 1.0.2 includes a top-level asynchronous immediately-invoked function expression (IIFE) that runs on package import. It contacts public Ethereum RPC endpoints to retrieve the latest transaction from a specific attacker-controlled wallet. From this transaction, it decodes two IPv4 addresses embedded in the 'to' field bytes. It then fetches XOR-encrypted JavaScript payloads from these IP addresses over HTTPS, decrypts the payloads, and executes them using eval. Additionally, it spawns a detached Node.js child process to run the decrypted payload. The code is obfuscated using Unicode escape sequences to hide critical strings such as 'require', 'child_process.spawn', and the attacker wallet address. This Ethereum-based dead-drop mechanism allows the attacker to dynamically update the payload host by posting new transactions, making the malicious payload dynamically controlled and rotated.

This malicious package executes arbitrary JavaScript code fetched from attacker-controlled servers every time it is imported, enabling remote code execution on the host system. The attacker can dynamically update the payload by changing the Ethereum transaction data, potentially leading to persistent and stealthy compromise of systems using this package. The use of eval and spawning detached Node.js processes increases the risk of executing arbitrary commands and code, which can lead to full system compromise or further malicious activities.

No official patch or remediation is currently documented. Users should immediately stop using postcss-theme-provider version 1.0.2 and remove it from their projects. Verify dependencies for this package and replace it with a trusted alternative. Monitor for any unexpected child processes or network connections to suspicious IP addresses. Since the malicious code is embedded in the package itself, remediation requires removing the compromised package version. Patch status is not yet confirmed — check the vendor advisory or trusted security sources for updates.